"In the last five years, LLVM has evolved from an academic project to the universal back-end of C, C++, and Objective C compilers. The key to its success is its performance and adaptability, both of which derive from its unique design and implementation."

From what I understand there was work being done by Mono developers using LLVM - IMHO I'd love to see Apple provide a bridge via C#/VB.NET support to encourage developers from the Windows world to actively consider opportunities in the Mac world.